[FEATURE] Change all programs key from YY-YY format (start and end years) to YYYY-YYYY format.

[sandeep-ps]

Can we use the start and end year to make the key so it's more dynamic? I'm ok if we want to open an issue for this, but we should make it dynamic since at some point we'll want to expose the start/end years so someone could generate different ranges of data.

Originally posted by @navarroc in #269 (comment)

[sandeep-ps]

This will also need frontend changes and may not be a high priority given that the current implementation works.